Yates said in a memo Monday that she is not convinced that Trump's order is lawful, or that its defense is consistent with the department's obligation to "always seek justice and stand for what is right."

Yates was appointed deputy attorney general by President Barack Obama. She became acting attorney general once Loretta Lynch left the position.

Her directive will be in place until she leaves the department, which will happen once the Senate confirms Sen. Jeff Sessions, Trump's pick for attorney general.